This invention generally relates to a facility for decomposing waste material to produce a useful compost; and more particularly, to a large scale, highly automated system for decomposing waste material.
Organic matter is naturally decomposed by various types of micro organisms, and the end product of such decomposition is frequently a stable material that is useful in supporting life by virtue of its soil nutrient properties. Many attempts have been made to duplicate the natural processes of decomposition, for such decomposition presents an excellent solution to the problem of usefully disposing of the large amounts of unhealthful organic waste materials produced in today's society. An example of this problem in one of its most important forms is the need to find a healthful and useful way of disposing of the huge amounts of refuse which are constantly accumulated in modern municipalities.
Although numerous attempts have been made to successfully apply the process of bacterial decomposition to municipal refuse on a practical commercial scale, few, if any, of these previous attempts have enjoyed success of any magnitude as evidenced by the fact that the vast majority of the cities in this country still dispose of municipal refuse by burying it or by subjecting it to incineration. Not only do the latter processes constitute a financial liability to the municipality, but they also are not a complete answer to the sanitation problem, since various odors and unhealthful air pollution result from incineration, and since the burial process usually allows the refuse to be exposed long enough to become infested with disease-carrying vermin.
There are several reasons why biological decomposition of municipal refuse has not been widely accepted as a means of disposing of such refuse. First, the time required to convert the refuse to a useful, or at least safe, final product has been of such duration that cities producing large volumes of such refuse have not found it practical to attempt to dispose of refuse in this manner. In some cases, treating the refuse with microorganisms to effect its decomposition and stabilization in a useful product has required more than a month. Secondly, the process of biological decomposition has all too frequently been accompanied by the evolution of noxious gases, or at least gases having a very undesirable odor. It is well known that these obnoxious gases are products of the putrefaction of organic matter by the type of bacteria which are characterized as anaerobic bacteria (that is, those which reproduce and thrive in the absence of oxygen). Nevertheless, the composting processes thus far utilized have not, as a rule, enjoyed a high degree of success in suppressing anaerobic bacterial action and in promoting the substantially odorless oxidative action of aerobic bacteria.
Another reason for the previous lack of widespread acceptance of composting as a means of disposing of municipal refuse has been the failure of many of these processes to yield a completely stable and innocuous product. In general, the stability of the final product can be increased, but at the sacrifice of an increase in the time required to completely compost and stabilize the refuse so that the solution of one of the problems only results in the aggravation of another. Moreover, prior art, large scale composting systems usually require a considerable amount of human labor, either to operate the system or various pieces of equipment used in the system, or at least to supervise that operation.